System for determining relative distance(s) and/or angle(s) between at least two points

ABSTRACT

Systems and method utilizing microelectronic devices for determining relative positions such as distances and/or angles between at least two points is described. The points may be locations of parts of the body such as the fingers on a person&#39;s hand. A first microelectronic device is adapted to emit magnetic signals and at least a second microelectronic device is adapted to receive the magnetic signals, wherein a controller is adapted to communicate with the first and second microelectronic devices. The second microelectronic device and/or the controller are adapted to determine a distance and angle between the first and the second microelectronic devices based on the strength of the magnetic signals received by the second microelectronic device.

This application claims the benefit of U.S. Provisional Application No.60/497,419 filed on Aug. 22, 2003. This application is acontinuation-in-part of U.S. patent application Ser. No. 10/391,424,filed Mar. 17, 2003; now abandoned which is a divisional of U.S. patentapplication Ser. No. 09/677,384, filed Sep. 30, 2000, now U.S. Pat. No.6,564,807; which is a divisional of U.S. patent application Ser. No.09/048,827, filed Mar. 25, 1998, now U.S. Pat. No. 6,164,284; which is acontinuation-in-part of U.S. patent application Ser. No. 09/030,106,filed Feb. 25, 1998, now U.S. Pat. No. 6,185,452; which claims thebenefit of U.S. Provisional Application No. 60/039,164, filed Feb. 26,1997. Additionally, U.S. patent application Ser. No. 09/048,827, filedMar. 25, 1998, now U.S. Pat. No. 6,164,284, claims the benefit of U.S.Provisional Application No. 60/042,447, filed Mar. 27, 1997. The subjectmatter of all of the aforementioned applications and patents are herebyincorporated by reference herein in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a first system in accordance with the firstexemplary embodiment of the present invention.

FIG. 2 is an illustration of a second system in accordance with thesecond exemplary embodiment of the present invention.

FIG. 3 is an illustration of a third system in accordance with the thirdexemplary embodiment of the present invention.

FIG. 4 is an illustration of an exemplary schematic block diagram of anemitter/transmitter portion of a microelectronic device.

FIG. 5 is an illustration of an exemplary schematic block diagram of areceiver portion of a microelectronic device in accordance with thepresent invention.

Corresponding numerals indicate corresponding elements throughout theseveral views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with exemplary embodiments, systems and method utilizingmicroelectronic devices (MEDs) for determining relative positions suchas distances and/or angles between at least two points is described. Forexample, the points may be locations of parts of the body such as thefingers on a person's hand. By determining the relative positions of thefingers, it is possible to determine whether the person is making afist, an open hand or any other form in between. Moreover, the relativepositions may be the distance(s) of certain objects from each other. Bymeasuring the magnetic field strength between at least twomicroelectronic devices the distance(s) and/or the angle(s) betweenvarious points in the body or inanimate objects may be calculated.

Each microelectronic device can be a microstimulator and/or amicrosensor. For example, a class of injectable/implantablemicroelectronic devices described in U.S. Pat. Nos. 5,193,539,5,193,540, 5,312,439, 6,164,284, 6,185,452, 6,208,894, 6,315,721,6,564,807 and incorporated by reference herein provide for stimulationof biological tissue or sensing of signals from biological tissue suchas nerves or muscles as well as physiologic parameters such as bodytemperature. Each device includes electrical stimulation circuitry andelectrodes configured in a form that is suitable for injection by meansof a hypodermic needle or insertion tool. The devices can be leadless orhave leads attached to them. Furthermore, each device may communicatethrough wireless or wired communication networks. In the case ofwireless networks, microelectronic devices receive power by eitherinductive coupling to an externally applied electromagnetic field or bymeans of an internal rechargeable battery. They receive digital commandsignals by telemetry. The packaging and materials of the microelectronicdevice are selected and designed to protect its electronic circuitryfrom the body fluids and to avoid damage to the electrodes and thesurrounding tissues from the presence and operation of themicroelectronic device in those tissues. In this regard themicroelectronic devices are hermetically sealed and unaffected by bodyfluids.

FIG. 1 is an illustration of a first system 100 in accordance with afirst exemplary embodiment of the invention showing a firstmicroelectronic device 110 and a second microelectronic device 112communicating with a controller 124. In the present embodiment, thefirst microelectronic device 110 is adapted to emit magnetic signals andthe second microelectronic device 112 is adapted to receive the magneticsignals from the first microelectronic device 110. The first and thesecond microelectronic devices may have similar or even identicalstructure and circuitry. This allows for more flexibility andscalability of the system. The controller 124, while communicating withthe first and the second microelectronic devices, can assign either thefirst or the second microelectronic device to transmit/emit magneticsignals or receive the same. In this manner, for example, the firstmicroelectronic device 110 can operate as a transmitter/emitter and thesecond microelectronic device 112 can operate as a receiver.

Referring to FIG. 1, in the first exemplary embodiment, the first systemmay, for example, be arranged such that the first microelectronic device110 is implanted in the biceps area of a person and the secondmicroelectronic device 112 is implanted in the forearm area of theperson with the controller 124 attached to the belt or the waist area ofthe person for convenience. The controller 124, in the alternative, maybe implanted in the body of the person. An external electronic device126 is also shown which is adapted to transmit power to the first andthe second microelectronic devices and also transmit command signals tothe controller 124. The microelectronic devices may be either RF-poweredor may include a rechargeable battery or a long-lasting primary cell.Examples of the RF-powered and the battery-powered microelectronicdevices contemplated in the embodiments of the present invention aredescribed in U.S. Pat. Nos. described above and incorporated byreference herein.

In the embodiments of the present invention, it is contemplated thatmagnetic signals instead of radio frequency (RF) signals are emittedfrom the first microelectronic device 110 and received by the secondmicroelectronic device 112. It is known that magnetic signals areattenuated over distance in accordance to the cube law. At distancesaway from a source of magnetic field, the strength of the magnetic fieldis reduced according to the following formula: H=Ho×(1/d)³ wherein H isthe strength of the magnetic field at a distance (d) away from thesource of the magnetic field H and Ho is a magnetic field strength at areference distance. In contrast, the RF field attenuates as a linearfunction in accordance to the following formula: H=Ho×(1/d); E=Eo×(1/d)where E is the electric field component of the RF field and Eo is anelectric field strength at a reference distance. The embodiments of thepresent invention advantageously utilize the emission and reception ofmagnetic field signals between the microelectronic devices. Magneticsignals are less prone to interferences from external sources. It shouldbe noted that generally there are more RF signal interference sources inthe environment than there are magnetic field interference sources.Moreover, since the magnetic field signals are reduced in strength overdistance at a much higher rate than the RF signals, then there are lesschances that external magnetic field sources in the vicinity of thesecond microelectronic device will interfere with the reception ofemitted magnetic signals from the first microelectronic device. The useof the magnetic signals has the further advantage that it propagatesbetter in body tissue than the RF signals.

According to the first embodiment, after implanting the first and thesecond microelectronic devices in the body by utilizing either ahypodermic needle or an insertion tool, a fitting or calibration routineis performed. The calibration routine involves generating magneticsignals by the first device and measuring the strength of the magneticsignals at the second device and also physically measuring thecorresponding distances between the two devices at various points. Acorrelation table is provided based on the corresponding magnetic signalstrengths and the distances between the two devices. The values of thecorrelation table may be stored in any set of receiving microelectronicdevices, such as the second microelectronic device 112 or the controller124.

As described above, the first microelectronic device 110 emits magneticsignals to be received by the second microelectronic device 112. Uponreceiving the magnetic signals from the first device, the second device112 measures the strength of the magnetic signal and based on thecorrelation table can calculate the distance between the two devices andcorrespondingly the distance between the two parts of the body, such asthe biceps and the forearm. As a result of the distance measurement, theposition and the angle of the forearm relative to the biceps isdetermined, for example, whether the arm is fully extended or bent. Itis further contemplated that the strength of the magnetic signalmeasured by the second device may be communicated to the controller 124where it can similarly perform the distance and angle computationsinstead of the second device 112.

FIG. 2 is an illustration of a second system 200 in accordance with thesecond exemplary embodiment of the invention. The second system 200comprises a first microelectronic device 210 a plurality of secondmicroelectronic devices 212-220 and a controller 224 in communicationwith the first microelectronic device and the plurality of the secondmicroelectronic devices. In the second exemplary embodiment, the firstmicroelectronic device 210 is adapted to emit a magnetic signal having afirst frequency and the plurality of second microelectronic devices212-220 are adapted to receive the magnetic signal having the firstfrequency. The first microelectronic device 210 and the plurality of thesecond microelectronic devices 212-220 may have similar or evenidentical structure and circuitry as described above in connection withthe first exemplary embodiment. Similar to the first exemplaryembodiment, the controller 224, while communicating with the first andthe plurality of second microelectronic devices, can assign either thefirst or any of the plurality of second microelectronic devices totransmit/emit magnetic signals or receive the magnetic signals. Thisallows for the ability to reconfigure the system for any desiredarrangement.

Referring to FIG. 2, in the second exemplary embodiment, the secondsystem may, for example, be an arrangement wherein the firstmicroelectronic device 210 is implanted in the palm of a hand and theplurality of second microelectronic devices 212-220 are implanted in thefingers. The controller 224 may be positioned in any desired locationsuch as on a belt of the person. It should be noted that the arrangementsuggested in the second exemplary embodiment may be implanted in anyother location in the body where a distance between and/or anglemeasurements of the body parts is desired.

With respect to the second exemplary embodiment, the firstmicroelectronic device 210 emits magnetic signals having a firstfrequency and the plurality of second microelectronic devices 212-220receive the magnetic signals. The plurality of second microelectronicdevices 212-220 measure the strength of the received magnetic signals.The values of the strength measurements of the magnetic signals arecompared to the values in the correlation table obtained by a method ofcalibration described earlier. By comparing the aforementioned values,the distance and/or angle measurement between the first microelectronicdevice 210 and the plurality of second microelectronic devices 212-220are determined. By determining the distance and/or angle of thepositions of fingers on a hand, the movements and the various forms thata hand can take is determined.

FIG. 3 is an illustration of a third system 300 in accordance with athird exemplary embodiment of the invention. The third system 300broadly comprises a first subsystem and a second subsystem and acontroller 324 in communication with the first and the second subsystem.The first subsystem 301 comprises a first microelectronic device 310adapted to emit magnetic signals having the first frequency and aplurality of second microelectronic devices 312-320 adapted to receivethe magnetic signals having the first frequency. The second subsystem302 comprises a third microelectronic device 330 adapted to emitmagnetic signals having a second frequency and a plurality of fourthmicroelectronic devices 332-340 adapted to receive the magnetic signalhaving a second frequency. The controller 324 communicates with thefirst microelectronic device, the plurality of second microelectronicdevices, the third microelectronic device and the plurality of fourthmicroelectronic devices and through communicating with these devices itconfigures them such that any device may operate as source of emittingmagnetic signals with a specific frequency or any device may receive themagnetic signals. It should be noted that in all of the exemplaryembodiments described the distance measurement operation can beperformed by either the receiving microelectronic device or thecontroller.

In the third system of the third exemplary embodiment, each receivingmicroelectronic device such as microelectronic devices 312-320 ormicroelectronic devices 332-340 comprises a resonator circuit in a formof an LC tank. The resonators are tuned to a central frequency Fo with apredetermined narrow bandwidth allowing for the first and the secondfrequencies to fall within the respective resonator bandwidth and bereceived and detected by each receiving microelectronic device. Themicroelectronic devices 312-320 and microelectronic devices 332-340 eachhave a digital signal processor (DSP) circuitry and each selectivelyprocesses the received magnetic signals such that the microelectronicdevices 312-320 detect the magnetic signals having the first frequencyand the microelectronic devices 332-340 detect the magnetic signalshaving the second frequency. In this manner, the two subsystems do notinterfere with each other when brought close together. It should benoted that when there are multiple subsystems, namely, more than two,the present embodiment provides for multiple frequency channels whereineach subsystem communicates on a specific frequency, thereby avoidingpotential interferences.

It should also be noted that in all of the exemplary embodimentsdescribed, a communication scheme such as atime-division-multiple-access (TDMA) may be implemented. For example, inorder to achieve a robust communication between each receivingmicroelectronic device and the controller, the controller commands eachmicroelectronic device to communicate with the controller at differentpredetermined time periods. This is performed where the controllertransmits a global time base signal to all receiving microelectronicdevices, wherein the global signal synchronizes the timing oftransmission of signals from the receiving microelectronic devices indiscrete time slots in a single frequency channel. In the alternative, afrequency-division-multiple-access (FDMA) or acode-division-multiple-access (CDMA) communication format between thecontroller and the receiving microelectronic devices may be implemented.In this case, the controller communicates with each of the receivingmicroelectronic devices on a different frequency.

FIG. 4 is an illustration of an exemplary schematic block diagram of anemitter/transmitter portion of a microelectronic device. Broadly, theemitter/transmitter portion of the microelectronic device comprises aclock generator 410, signal generator 412, a buffer 414, and an LC tank416.

FIG. 5 is an illustration of an exemplary schematic block diagram of areceiver portion of a microelectronic device. Broadly, it comprises anLC tank 510, an amplifier 512, a mixer 514 with an associated localoscillator 516, a filter 518, an analog-to-digital (AID) 520 converterand DSP 522.

It should be noted that any of the embodiments of the microelectronicdevices and the controller described herein may be implantedsubcutaneously or percutaneously in a body of a living organism orplaced on the surface of the body. Generally, when the apparatus isimplanted subcutaneously, it utilizes wireless communication although insome circumstances it may utilize wired communication with the externalunit. The dimensions of the microelectronic device are less than about100 mm and 10 mm longitudinally (axial) and laterally respectively. Thisprovides for a more efficient injection of the device into the body.

While the invention has been described by means of specific embodimentsand applications thereof, it is understood that numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the spirit and scope of the invention. It is therefore tobe understood that within the scope of the claims, the invention may bepracticed otherwise than as specifically described herein.

What is claimed is:
 1. A system for determining relative positions ofbody parts, the system comprising: a first implantable microelectronicdevice adapted to emit magnetic signals having a first frequency; aplurality of second implantable microelectronic devices adapted toreceive the magnetic signals having the first frequency; a controller incommunication with the first implantable microelectronic device and theplurality of the second implantable microelectronic devices.
 2. A systemof claim 1, wherein the controller commands each of the plurality ofsecond implantable microelectronic devices to communicate with thecontroller at different predetermined time periods.
 3. A system of claim1, wherein the controller commands each of the plurality of secondimplantable microelectronic devices to communicate with the controlleron different frequencies according to afrequency-division-multiple-access (FDMA) communication format.
 4. Thesystem of claim 1, wherein each of the plurality of second implantablemicroelectronic devices measures the strength of the received magneticsignals and wherein each one of the plurality of second implantablemicroelectronic devices is capable of determining the distance betweenitself and the first implantable microelectronic device.
 5. The systemof claim 4, wherein each of the plurality of second implantablemicroelectronic devices transmits the measurement of the strength of thereceived magnetic signals to the controller and wherein the controllerdetermines each distance between the first implantable microelectronicdevice and each of the plurality of second implantable microelectronicdevices.
 6. The system of claim 1, wherein the first implantablemicroelectronic device and the plurality of the second implantablemicroelectronic devices are less than 6 mm in lateral dimension and lessthan 60 mm in axial dimension.
 7. A system for determining relativepositions of body parts, the system comprising: a first subsystem,comprising: a first implantable microelectronic device adapted to emitmagnetic signals having a first frequency; a plurality of secondimplantable microelectronic devices adapted to receive the magneticsignals having the first frequency; a second subsystem, comprising: athird implantable microelectronic device adapted to emit magneticsignals having a second frequency; a plurality of fourth implantablemicroelectronic devices adapted to receive the magnetic signals havingthe second frequency; a controller in communication with the firstimplantable microelectronic device, the plurality of second implantablemicroelectronic devices, the third implantable microelectronic deviceand the plurality of fourth implantable microelectronic devices.
 8. Thesystem of claim 7, wherein the plurality of second implantablemicroelectronic devices and the plurality of fourth implantablemicroelectronic devices each comprise a resonator having a predeterminedbandwidth.
 9. The system of claim 8, wherein the first frequency and thesecond frequency fall within the resonator bandwidth.
 10. The system ofclaim 9, wherein each of the plurality of second implantablemicroelectronic devices and the plurality of fourth implantablemicroelectronic devices comprise a signal processor means, whereby eachselectively processes the magnetic signals having the first frequencyand the second frequency to determine the strength of the magneticsignals received.
 11. The system of claim 10, wherein the firstimplantable microelectronic device, the plurality of second implantablemicroelectronic devices, the third implantable microelectronic deviceand the plurality of fourth implantable microelectronic devices are lessthan 6 mm in lateral dimension and less than 60 mm in axial dimension.12. A system for determining relative positions of body parts, thesystem comprising: a first microelectronic device adapted to emitmagnetic signals having a first frequency; a plurality of secondmicroelectronic devices adapted to receive the magnetic signals havingthe first frequency; said first and second microelectronic devicessuitable for subcutaneous injection by an insertion tool; a controllerin communication with the first microelectronic device and the pluralityof the second microelectronic devices.